The method of pituitary injections has been used in our country for
fish rearing purposes for nearly 30 years. This method, which ensures the
controlled development of the spawning state, has been evolved on the basis
of analysis of the mechanism of the system which is chiefly responsible for
the sexual cycle and spawning control. Generally speaking, the reproductive
system in all fish is similar but at the same time it is highly adaptable
due to the propagation process adaptations of numerous and diverse species.
(See Fig. 1)

This simplified diagram shows the organs of the reproductive system
and their functional relations during the period when females and males
become spawners. A profound analysis of these complex interrelations, as a
means of realization of the integrated development of the internal and
external parts of the organism is a fascinating and urgent problem.

The development of gonadotrophin and the entire neurohormonal mechanism
of the reproductive system control: exteroceptors-analysers, the hypothalamus
with vegetative nuclei and their neurosecretory cells, the hypothalamal
pituitary neurosecretory path, the pituitary gland, sex glands, their interoceptors
and afferent relations, the central nervous system, and spawning
behaviour is an indication of aromophosis, which is an essential factor in
the evolution of the vertebrates, fish and Cyclostoma in particular.

The idea of controlling the spawning state development is based on this
system and is extremely simple.

Fishery management experience has shown that spontaneous spawning state
development is not determined only by the temperature and hydrochemical conditions.
The combination of conditions required for the development of the
spawning state by a given species comprises some specific features characterizing
the “spawning situation”. Convincing illustrations of the above
statement are: application of fresh sod in case of a delay in spawning as
a result of the sitting of the pond beds, soft vegetation is very popular
in carp rearing; adequate spawning of Vimba vimba natio carinata in
running water ponds with pebble bed soils (the Kuban vimba and chalcalburnus nursery and the Don sturgeon and vimba hatchery); mass spawning of orpha
(Leuciscus idus m. orpha) within a very short time following the treatment
of the pond with bunches of fresh green juniper branches and other cases.
When some elements of the required combination of conditions are available,
it is the exteroceptor response to a number of specific features of spawning
grounds required by a given species, that starts the sequence of phenomena
characterizing the spawning state development.

Such imitation of spawning ground conditions, used as a method of the
spawning state development control, without additional influencing, does
not meet commercial production requirements because this procedure cannot
be effectively planned as far as fish output indices and calendar terms go.
Moreover, use of this method of reproduction of wild fish such as the
Acipenseridae and many bony migratory and semi-migratory fish in natural
water bodies involves complicated construction measures and does not meet
the economic requirements.

To obtain eggs and sperm of such fish, the method of pituitary injections
has been developed and is being successfully applied in fish culture. For
instance, all eggs are obtained only by this method on the sturgeon farms
on the lower Volga, Ural, Kura, Kuban, Don, Dnieper and other rivers
(Guerbilsky, 1941, 1947).

The method of pituitary injections has become especially important in
fish culture because of dam construction. As a result of this construction,
many rivers have undergone such changes that propagation of some migratory
species is either inhibited considerably or even halted to such a degree that
the formerly effective natural propagation has to be substituted by the operation
of fish farms.

Application of the method of pituitary injections allowing us to shift
the terms of spawning or to cause a mass spawning of a considerable number
of fish for production purposes, is beneficial for pond fisheries as well.
Furthermore, this method may be widely used in fish acclimatization processes.
It facilitates considerably fish management acclimatization measures, fish
hybridization work and, finally, selection of various pond culture species.

When practicing pituitary injections, we use the hormone which is
indispensable for each fish to develop the spawning state, whatever the water
body where it propagates.

For all fish, as well as other vertebrates, this hormone is a common
element indispensable in the functioning of the reproductive system.

When guiding the development to the spawning state, we use this same
hormone but we start the process with the injection of the hormone, skipping
other initial stages, i.e., the influence of the spawning ground conditions
and all consequent phenomena, the gonadotrophic function of the pituitary
gland of the recipient included.

The reaction brought about by this kind of treatment is the transition
of the fish from the fourth stage of maturity to the fifth one. Therefore,
our main interest lies in the range of the pituitary gonadotrophin influence
and in some essential details of the pituitary injection application in
fish culture associated with it.

The effect of any influence on the organism depends, both on the nature
and intensity of the influence, as well as on the state of the organism
responding to this influence. Therefore, the effectiveness of pituitary
injections depends, first of all, on the coincidence of the time of treatment
with the suitable period of the sexual cycle.

The longer this period, the more opportunities for application of the
method of pituitary injections. Therefore, it is necessary to consider in
our case the peculiar features of gametogenesis and sexual cycle of the
fish concerned.

The substantial dependence of the processes occurring in the organism
on natural seasonal phenomena is especially manifest in fish and all other
animals with a relatively unstable temperature of the body.

One of the most vivid manifestations of these relations is the seasonal
cycle of the reproductive system.

The study of fish ovogenesis has disclosed the stages of this process.

The more or less smooth process of the ovocytes growth, due to the
build-up of the cytoplasm and nucleus mass (“protoplasmic growth”), is
followed by a qualitatively different and relatively faster growth process,
due to the origination and accumulation of yolk (“trophoplasmic growth”).

On attaining the ultimate size due to the trophoplasmic growth, the
ovocyte is able to convert to a qualitatively different state characterised
by pre-ovulation nuclear processes and (in the ovocytes of the majority of
fish) by transformations in the aggregate state of trophic inclusions.
These processes terminate in an ovulation. A remarkable adaptive feature,
essential for adequate propagation, is the ability of fish ovocytes, to
become relatively stabilized whenever the conditions required for the
transition from the protoplasmic growth to the prophoplasmic one and from
the state of the completed trophoplasmic growth to preovulation nuclear
changes are lacking.

At other phases of ovogenesis such a delay may upset the development of
ovocytes. This phenomenon accompanied by the mass atresia is observed, for
instance, in fish barred by dams on their spawning migration run and at
spawning temperatures in case preovulation changes start in ovocytes.
Ovulation and spawning, however, do not occur since other factors of the
required condition complex are lacking.

The growth of ovocytes in fish spawning in spring is completed shortly
before egg shedding begins. Hence, the preovulation nuclear processes and
ovulation follow immediately after the ovocyte growth completion. However,
the delay in the ovocyte development at the completed trophoplasmic growth
stage is characteristic for many fishes spawning in spring. This is another
important adaptation, because such fish can spawn in spring immediately, as
soon as the required natural conditions develop. This, as is known, takes
place at different times depending on the meteorological characteristics
of the year.

Such fish retain the ability to become spawners within a short period,
subject to suitable conditions, throughout the whole winter. For instance,
loach females taken from water bodies in any of the winter months after a pituitary injection at a temperature of 15 to 20°C, start spawning within
45 to 50 hours and preovulation processes in ovocytes, ovulation and the
subsequent development of the progeny proceed normally (Tchernyshev, 1941).

Hence, the pre-spawning stage with some fish may last for a rather
long time.

The process of fish spermatogenesis, similarly to other animals,
differs from ovogenesis greatly.

However, during fish spermatogenesis, delays in the development at
some stages of the sexual cycle may be also incident. For instance, the
milt normally maintains for a long time the state prior to the next cycle
of spermatogenesis. This state is characterized by a prolonged stage of
primary spermatagonia. Another typical delay in the sexual cycle is the
state of the completed spermatogenesis, the milt ampullas being filled with
mature sperm. The milt of quite a number of fish spawning in spring preserves
the above condition throughout the whole winter preceding the spawning.

It has been proved on males as well as females of many fish that males
in such milt condition can develop the spawning state as a result of pituitary
injections at any time in winter, subject to suitable spawning
temperatures required by a given species.

This data is absolutely indispensable for an adequate conception of
range of the gonadotrophin influence of the pituitary gland. Irrespective
of whether we deal with fish characterized by a partial or one-time spawning,
the state of the ovocytes of the older generation and the completion
of the spermatogenesis process in the milt ampullas, respectively, are the
main indications of the completion of the fourth stage of maturity.

The most characteristic feature of the ovocyte development of the older
generation (at the fourth stage of maturity) is their polarization, usually
occurring only upon the completion of vitellogenesis. The ovocyte polarization
consists of the nucleus travelling, together with the parts of cytoplasm
free from yolk, towards the micropyle so that the future position of
the animal pole of the ovocyte is determined by the micropylar foramen
towards which the nucleus is traveling during the ovocyte polarization.
The eccentric position of the nucleus indicates that the egg is maturing.
When the nucleus is displaced completely, it is seated immediately under
the micropyle in the protoplasmic disc at the animal pole.

On the basis of our previous experience gained in the work with the
Acipenseridae, we can state that the central position of the nucleus in
the ovocytes of the older generation of these fish coincided in our experiments
with the negative results of the pituitary injections, thus the
polar differentiation of the ovocytes of the older generation being
criterion for the use of pituitary injections.

Another significant criterion, equally applicable both to the Acipenseridae
and to bony fish, is the condition of the nucleolar apparatus in
the ovocyte nucleus. During the whole period of the protoplasmic and
trophoplasmic growth, the ovocyte nuclei are characterized by a great number
of nucleoli tightly contiguous to the nucleus membrane. The travel of the
nucleoli towards the nucleus center and their dissolution in caryolymph is
a very important and characteristic initial indication of the transition
of the nucleus from embryonic bubble stage to meiosis. This phenomenon is extremely important for application of the method of pituitary injections.
As a direct experiments showed, preovulation processes, beginning from the
travel of the nucleoli, occur under the influence of the pituitary gonadotrophic
hormone, i.e., fall within the range of its effect.

As mentioned above, the main process during this period is the transition
of the nucleus to the metaphase of the first meiotic division. The
entire complicated process, which is inadequately termed by some authors
as “the dissolution of the nucleus”, should be broken up into the following
phases: travel of the nucleoli from the nucleus periphery to its
central region; polarization and dissolution of the nucleoli; emergence
of filiform chromosomes; isolation of the whole set of chromosomes from
the composition of the embryo sac into a generative nucleus of a considerably
small size; transition of the generative nucleus to the metaphase of the
first meiotic division; the first meiotic division, and emergence of the
first reduction body suspension of meiosis in the stage of metaphase or
anaphase of the second division, which generally occurs after the ovulation
and ends upon penetrating of a sperm into an ovum. This pattern of the
ovum maturing process can vary in particulars but on the whole, it is
typical of all fish.

To ensure effective application of pituitary injections and to forecast
the moment of maturing precisely enough, it is essential to have an idea
of the duration of this process occurring under the influence of the gonadotrophic
hormone. Special experiments were carried out to elucidate this
problem. (T.I. Faleeva, 1953); (B.N. Kazansky, 1953).

Simultaneously with pituitary injection, by means of a metal probe or
through an opening, samples were taken of the ovocytes of the sturgeon
females. Then similar samples were taken from the same female every five
hours during the period of maturing after the pituitary injection until the
completion of the ovulation. On the basis of the experiment, it was revealed
that, at the temperature of 18 to 20°C during the first five hours after
the pituitary injection, the nucleoli disappear simultaneously, with chromosomes
emerging in the nucleus in the form of pairs of crossed, slightly
nodular threads. At the same time the rear edge of the nucleus becomes
scalloped and this section of the nucleus displays an accumulation of plasm,
almost devoid of yolk. During the following five hours, as the nucleus
volume decreases, the accumulation of protoplasm free from yolk near the
nucleus increases, so that 9 to 10 hours after the pituitary injection
treatment the nucleus volume drops about 300-fold. (B.N. Kazansky, 1953).
Subsequently, this transformed nucleus undergoes changes typical of the
prophase which immediately precedes the first meiotic division. Fifteen
hours after the injection one can observe the metaphase of the first division
of maturation and 20 hours later - 1.5 to 2 hours prior to the completion
of the ovulation - the nucleus develops the state of metaphase of the second
division of maturation. There is no doubt that the nuclear processes
described occur due to the gonadotrophic hormone of the pituitary both in
nature and in the experiments.

As mentioned above, the rate of these processes depends on temperature - and, within a certain temperature range, it is in direct proportion to
the temperature. The correlation between the duration of the preovulation
nuclear processes and ovulation and the duration of embryogenesis (the
duration of the embryo development till hatching) at a given temperature
is based on this and is of great importance for scientific and fishery management purposes. Recently T.A. Detlaf and her collaborators have
ascertained that the duration of the period lasting from the injection to
the complete development of the fifth maturity stage by the sturgeon is
from 17 to 23 percent of the time required for the completion of the embryogenesis
at a given temperature. This has provided the authors an opportunity
to recommend convenientcalculation tables which help determine the most
expedient time for opening females and obtaining eggs at sturgeon hatcheries.
This permits us to examine much fewer females, to raise the production
quality and to make the planning of the work easier. (T.A. Detlaf and
S.E. Zubova, 1962).

When dealing with bioactive substances, such as the gonadotrophic
hormone, dosage is of vital importance. This has caused considerable
difficulties which cannot be considered to be overcome until the present
moment. While the exact determination of dosage is quite feasible when
dealing with chemically pure preparations, synthesized hormones, for instance,
dosage of preparations which comprise various by-substances apart form the
required hormone is complicated and difficult.

For pituitary injections we use acetone-treated pituitaries ground to
powder. It is made of fatless and completely dried pituitaries of fish.
The share of hormone pure gonadotrophic in the whole mass of the powder,
prepared as suspension and injected by means of a syringe into a special
muscle of a fish, is not known. It is especially difficult to find an
answer to this question because the concentration of the gonadotrophic
hormone in the fish pituitary does not remain the same during the year and
varies both within the seasonal cycle and the whole life of a fish. Therefore,
expression of the optimum dosage of the acetone-treated pituitary
powder in weight units, may lead to serious errors and failures in experiments
and production.

In such cases the endocrinologists apply test-objects which permit the
use of biological units to measure the preparation activity. For instance,
our laboratory uses loach units to measure the fish gonadotrophic hormone
(Kazansky and Nusenbaum, 1947; Kasansky, 1949). The unit is assumed to be
the amount of powder (in milligrams) which is sufficient to cause ovulation
in a loach female of average weight in the fourth stage of maturity at room
temperature. Having developed such methods of testing, or in other words,
the methods for determination of the preparation activity, we can easily
convert biological units into weight units. For instance, when determining
the minimum effective dosage of pituitary of the wild carp, it turned out
that the dosage was 0.2 mg per one female loach weighing 35 to 45 g at a
temperature of 16 to 17°C. Thus, one milligram of the powder made of the
acetone-treated pituitary of the wild carp represented five loach units
of the gonadotrophic hormone.

In the course of the application of the method of pituitary injections
in carp pond fisheries, certain results were obtained which are essential
for understanding the functional mechanism of the spawning state development
and for further perfection of this method in fishery management
practices. The experiments carried out in 1941 in the Novgorod region
(Chernyshov, 1941), in the Estonian S.S.R. (Guerbilsky and Nusenbaum, 1949) and in the Latvian S.S.R. (Kazansky, 1950) proved that the application of
the injection method in carp culture permits us to cause simultaneous
spawning, subject to favorable temperatures, at the desired time and to
plan all fish culture work connected with fry rearing (Chernyshov, 1941).
Later the dose of pituitary was determined empirically within the limits
of spawning temperatures (25 to 30 loach units for females and 10 to 15 for
males). One mg of dry powder made of acetone-treated pituitary of the
wild carp in the fourth stage of maturity (i.e., in late autumn, winter or
spring, prior to spawning) contained from 3 to 5 loach units and bream
pituitaries contained 3 to 4 loach units. With this dosage spawning
commenced 20 to 36 hours after the injection (Kasansky, 1950).

Table I

Effect of various doses of pituitary on the quality of eggs of the Kurinsky
Sturgeon (S.V. Bank, 1949). Water temperature 13.3 to 15.2°C.

Item

Female body measurements cm.

Quantity of eggs g.

Date and time of opening

Eggs weight kg

Egg waste at the neurula stage

1

207/179

51.2

May 1- 10:30

12.450

67.3

Dosage-400 loach units, 68.6 percent of waste

2

183/156

50.5

" 10:45

5.900

58.0

3

197/173

45.5

" 11:10

9.950

73.3

4

186/157

41.5

" 11:30

2.100

51.0

The minimum wast percentage -51.0

5

188/162

49.0

" 11:50

6.700

91.3

1

193/168

43.0

" 12:25

6.750

7.5

Dosage - 200 loach units 12.4 percent of waste

2

169/155

43.5

" 12:45

6.450

3.4

3

190/168

44.0

" 13:05

5.500

22.0

4

200/171

42.5

" 13:25

11.700

7.3

The maximum waste percentage 22.1

5

195/170

51.0

" 13:50

11.000

22.1

(note: All ten females were collected in the course of one day, delivered to the fish farm
and treated with an injection at the same time and were kept under all other equal
conditions).

Czechoslovakian fish culturists have attained considerable suceess in
the application of the pituitary injections, with a view to securing early
mass carp spawning in spawning ponds. Janecek (1953) cites the best dosage
determined empirically of one and one half pituitaries per female. High
doses (four pituitaries) produced a pathological result: the fish kept
swimming violently for ten hours but did not spawn, the carp organism
developing considerable pathological changes as a result.

Havelka cites good results but points out various abnormalities in the
spawning process and also emphasizes the problem of dosage under “hypophysation”
application conditions (Havelka, 1952). Such well-know Czechoslovakian
fish culturists as Kostomarov and Hochman pay special attention to selecting
the precise dosage and underline the detriment caused by excessive doses
(Kostomarov, Hochman, 1957). On the basis of comprehensive investigations,
these authors believe that the optimum dosage is 0.7 to 0.8 mg of acetone-treated
pituitary per 1 kg of the female live weight.

The investigation conducted by Czechoslovakian authors Cernaev and
Bena is of particular interest (Cernaev, Bena, 1954). They observed an
accelerated development of the spawning state by the mirror carp “nests”
under the so-called “combined stocking” conditions, i.e., when the treated
males were stocked into the spawning ponds together with intact females
and the treated females together with intact males. In this case we observe
distinctive interaction of the sexes when becoming spawners and a manifestation
of the leading role of the nervous system in this process.

There is still another methodological aspect to be considered. Generally,
when applying pituitary injections, we administer the whole dose of the
hormone at one time but this is not the way it occurs under natural conditions.
The build-up of the acting gonadotrophic hormone takes place gradually
as it is released from the pituitary gland, so that its effect is prolonged.
If the organism is ready to develop the spawning state, this difference
is probably of no significance. When intending to do this with regard to
an organism which is not quite ready, when the polarization of the older
ovocytes is not yet completed or if the development of this process in
various ovocytes of the same generation is asynchronous, then it is quite
possible that partial injections, i.e., administration of the dose by
portions, may be quite beneficial.

The experiments of this kind contribute to lowering production losses
and are of scientific and practical interest. It is the gradual (in two
stages) administration of the powder suspension of acetone-treated pituitaries
that has proved to be an extremely important variant of the method
when dealing with the White Amur and the Hypophthalmichthys molitrix Val. Fish culturists in China (mainland) and Konradt came to the above conclusion
independently, while rearing these species on pond fish farms (Konradt, 1961).
He theoretically substained the following pattern of influence on White
Amur and Hypophthalmichthys molitrix Val: if the permissible dosage of the
pituitary substance for White Amur and Hypophthalmichthys molitrix Val
spawners is 14 to 16 mg per female weighing 8 to 10 kg, it should be administered
by portions. At first, a very small dose of 2 to 3 mg per female is
required for leveling the gonad conditions. This dose is too small to
induce ovulation in fully mature females. In less mature females, this
dose can induce preovulation nuclear changes in the ovocytes within a short
period of time and prepare the fish organism for a positive reaction to the
next injection of the permissible dose of the hormone. We recommend administration
of this dose 24 hours after the preparatory injection.

The method of pituitary injections is used in many countries. For
instance, the American specialists (Atz and Pickford) emphasize the possibilities
of the wide use of this method. (Atz and Pickford, 1959).

The method of pituitary injections has been tested by long-term production
practice and has become routine in fish culture and fish acclimatization
work. It is very important in sturgeon raising, the basis for intensification
of the semimigrating fish reproduction farms, a method successfully
applied in carp culture and also in fish selection and hybridization
work.

However, the experimental work on hormonal control of the fish sexual
cycle and on controlled spawning is not completed at this stage. It is
still continuing in order to overcome some difficulties arising when the
pituitary injection method is applied. It is evident from the above that
the precise dosage of the preparation under production conditions poses
considerable problems. We should also add that, as application of the
method in fish culture develops on an ever-growing scale, the demand for
pituitaries increases along with the involved difficulties in their mass
procurement. Therefore, the tendency of looking for a substitute of similar
effect, production and dosage of which could be carried out under industrial
conditions at pharmaceutical plants, is quite justified.

In 1947 our laboratory, in collaboration with the endocrinological
staff of the Central Institute of Obstetrics and Gynecology, worked out
methods for diagnosis of early pregnancy with the aid of loach as test
objects. The loach ovocytes attained maturity and females ovulated after
an injection of four ml of urine of a pregnant woman, the females shedding
eggs 24 to 72 hours after the treatment. The highest percentage (98.57)
of positive reaction occurrence was recorded with the fish treated with the
urine of the women in the 7th to 12th week of pregnancy. Injections of
urine of 223 healthy non-pregnant women at the ages of 17 to 40 did not
produce a single case of positive reaction. (Guerbilsky and Kirshenblat,
1947). This is because urine blood, serum and various tissues of pregnant
women contain chorial gonadotrophin which is the acting agent of such injections.
Later Kirshenblat used this reaction for the quantitative determination
of the chorial gonadotrophin content in tissues, blood and urine, the
quantity of this hormone being expressed in “loach units” (Kirshenblat,
1950). For the first time we received choriogonin manufactured at the G.
Richter chemical works in Budapest, owing to the courtesy of A.A. Neifach.
The staff of his laboratory (The Institute of the Animal Morphology, A Sc
U.S.S.R.) uses this preparation generally in obtaining loach eggs in winter for the purpose of cytological and embryological investigations. The first
series of our experiments was carried out on loach and ruff females in March-April
1964. The results are shown in Table 2.

The following conclusions were drawn on the basis of these experiments:

Choriogonin, as well as acetone-treated fish pituitaries, is
suitable for artificial maturing of loach and ruff females from the
fourth to the fifth maturation stage and for obtaining mature eggs
from them.

Subject to favorable results obtained in the leading fishery
enterprises in spring and autumn, the organotherapeutic preparation-choriogonin,
dosed in mouse units, will serve as a good aid for fishery
management in dealing with spawners (Guerbilsky, 1964).

In 1964, in cooperation with our staff members P.E. Garlov and
A.A. Bojev, we conducted similar research on zander, wild carp, bream
and Vimba vimba at the Aksaisk-Don hatchery. The experiments were a
success in the case of zander only. The three specimens of carp did
not respond to the treatment at all, despite considerable doses, for
instance, 1,500 mEq in the case of bream. But zander females developed
from the fourth maturation stage to the fifth stage with 250 to
500 mEq at 10° to 14°, the lower threshold of the dosage effectiveness
being around 150 mEq.

Positive results of similar experiments on zander were obtained the
same year by our laboratory staff members I.A. Barannikova and I.I.
Saenko on the Volga River.

The studies with regard to other species continued in 1965.

The investigations of another possible substitute for acetone-treated
pituitaries are of great interest as well. This is the blood
serum of mares, with foal preparation SZhK. The results of the application
of this preparation on carp and trout pond farms are described by
Bulgarian culturists Bratanov, Dikov and Danjchev (1963). The authors
set themselves the following tasks:

Acceleration of egg and sperm shedding processes and fertilization during the first warm days in spring.

Obtaining more alevins of the first spawning with the same number of females and water area.

Creation of biological prerequisites for earlier maturing and early shedding of subsequent portions of eggs.

The following stimulants were used: SZhK from a mare in the second
month of pregnancy (intramuscular injections of 5 ml; 700 to 1,000 mEq
in 1 ml); preparation “Estrovet” (2 ml; 50,000 mEq and “Hyophysin
forte” (2 ml intramuscular injections).

After treatment, the females were stocked into the spawning ponds.
The beginning and duration of the spawning behavior were recorded. The
final estimation of the results was performed on the 21st day after hatching by calculating the alevins. The advantages of one or another type of influence were evaluated by comparing with the check intact spawners which had spawned at the same time in other ponds. Here are some of the figures cited by the authors: in all three series of experiments the
treated spawners produced more alevins than the intact ones; after the
hypophysin injection it was more by 29.4 percent Estrovet by 33.6 percent
and SZhK by 38.7 percent. Similar experiments in 1959 and 1960 yielded
the same data. When it comes to the evaluation of these results, certain
differences such as the considerable variation of the individual fecundity
of the mirror carp females between the intact fish and the experimental
series as well as within all the three experimental series were observed,
and the results, therefore, are not convincing enough for the forming of
an unprejudiced opinion on the effects of various hormonal influences.

Table 2. Artificial Maturing of Loach and Ruff Females (the 4th–5th
stages) as a result of choriogonin treatment

DosagemEq

Water temperature,°C

Number of females

Duration hours

Positive result

Negative result

Percent of fertilization

Loach (the experiment carried out in cooperation with K.D. Zueva and P.E. Garlov)

250

19–21

3

24

3

0

40–50

150

19–21

3

40–41

3

0

Late collection egg over maturing

250

12–15

3

60–65

3

0

80–90

50

12–15

3

74

1

Ruff (the experiment carried out in cooperation with T.I. Faleeva)

150

13–16

2

70

2

0

Nearly 100

100

12–15

3

90

3

0

-- " --

50

12–15

3

90

3

0

-- " --

25

12–15

2

90

2

0

-- " --

10

12–15

3

96

2

1

-- " --

100

20–23

3

44–65

3

0

90–97

50

20–23

3

44–65

3

0

90–97

25

20–23

3

44–65

3

0

90–97

10

20–23

3

65

1

2perished

90–97

Summarizing the results of their work, the authors conclude that the
SZhK treatment produces the strongest effect and that, by means of hormonal
injections, it is possible to reduce the duration of the spawning process,
depending upon the climatic and physiological conditions and that this
opens prospects for better organization of fishery management measures.

The experiments conducted by many authors in a number of countries and
the integration process of the pituitary injection method into fish culture
practice have contributed to the perfection of this method. They have
extended the scope of its application and have provided new opportunities
for its further development.

Some encouraging progress has also been made in attempts to find new
hormonal preparations as substitutes for acetone-treated pituitaries.

Within the same period of time ichthyology accumulated new and valuable
data on sexual cycles; gametogenesis and control of these processes in
various fish species.

The studies of the localization of the gonadotrophic function in the
pituitary gland of the bony fish (Kazansky and Persov, 1948) and in the
Acipenseridae (Barannikova, 1949) are of considerable importance. Our
knowledge of the range of influence of the pituitary gonadotrophin has been
enriched.

Administering considerable doses of acetone-treated pituitary by portions,
Sakun has shown that it is possible to bring about meiotic phenomena in
salmon ovocytes prior to the completion of the trophoplasmic growth stage
(Sakun, 1963). In the course of the experiments on macropodes, the role of
the pituitary gonadotrophin in determining the complicated forms of the
spawning behavior was investigated (Faleeva, 1963, 1965). The neurosecretion
phenomena in the lateral vegetative nucleus of the hypothalamus have been
studied and the synchronism of these phenomena, as the spawning period of
the wild carp and mirror carp begins, has been established (Polyanov, 1951).
The role of the hypothalamus pituitary neurosecretory system in determining
the spawning migration of the salmonids and sturgeons has been studied
(Barannikova, 1961, 1964, 1965).

All the investigations listed above and many other studies of functional
bases for specific adaptations involved in fish propagation contribute
to discovering new ways of controlling these processes which will remain
an urgent task of fish culturists engaged in working out techniques of fish
stock reproduction for many years to come.

The high abundance and extensive range which are the main indications
of the species' prosperity, i.e., its biological progress, are based on the
inherent hereditary systems of specific adaptations, as well as on those
developed in the process of its evolution.

The understanding of these adaptations and their profound analysis form
the theoretical basis of the technical control of the abundance and distribution
of food fish for the purposes of fishery management.

Detlaf, T.A. and S.E. Zubova, 1962 Relation of the duration period of the
maturation and embryogenesis of the sturgeon and Acipenseridae.
Report of the Academy of Science of the U.S.S.R., Vol. 143, N 3

Faleyeva, T.I., 1953 Cytomorphological data on the maturation and ovulation
processes of sturgeon and Acipenseridae. Report of the Academy
of Science of the U.S.S.R., Vol. 91, N 1

Faleyeva, T.I., 1965 Functional bases of the spawning behaviour and care of the
fish for the breed. Edition “Science”.

Guerbilsky, N.L., 1941 Method of pituitary injections and its role in fish
culture. Publication of the Leningrad State University.

Guerbilsky, N.L., 1947 Actual state and perspectives of the method of pituitary
injections in fish culture. Transactions of the Fish Culture
Laboratory, Vol. I. Leningrad.

Guerbilsky, N.L., 1956 The role of the nervous system during the transition of fish
organism into the spawning state. Transactions of the Karelian
Branch of the Acadmy of Science of the U.S.S.R., Vol. 5,
Petrozavodsk.

Guerbilsky, N.L., 1964 Is it possible to replace acetone-treated pituitary by other
preparation in fish culture? Information of the Leningrad State
University No. 15, Biological Section, Issue 3, Leningrad.

Kazansky, B.N., 1953 On the egg maturation and ovulation of sturgeon. Report of
the Academy of Science of the U.S.S.R., Vol. 89, N 4.

Kazansky, B.N. and L.M. Nusenbaum, 1947 Loach as a test-object to determine the
gonadotropic activity of the fish pituitary preparations.
Transactions of the Fish Culture Laboratory, Vol. I, Leningrad.

Kasansky, B.N. and G.M. Persov, 1948 Localization of the gonadotropic function
in the pituitary gland of the fish. Reports of the Academy
of Science of the U.S.S.R., Vol. 61, N 1.

Konradt, A.G., 1961 Conditions for rearing plant-eating fish in the pond fish
farms of the Soviet Union. Scientific-technical Bulletin of
the State Research Institute of Fresh Water Fisheries N 13–14,
Leningrad.

Polenov, A.L., 1950 Morphology of the neurosecretion cells of the hypothalamus
and the synchronism of these cells with gonadotropic function
of the wild carp and mirror carp. Reports of the Academy of
Science of the U.S.S.R., Vol. 73, N 5.

Sakun, O.F., 1963 Cytological and experimental study of the completion growth
stages and maturation of the ovocytes. IV Congress of Embryologists.
Theses of the reports. Edition of the Leningrad State
University.

Tchernyshov, O.B., 1941 First results of the pituitary injections application
in carp culture. “Method of pituitary injections”. Publication
of the State Leningrad University.